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PR3124 > Infectious disease & CDI > Flashcards

Infectious disease & CDI Flashcards

1
Q

Definition of Acute Infectious Disease

A

Acute: Increased freq of defecation lasting < 14 days
Diarrhoea: >= 3 loose/liquid stools OR
More frequent than normal
- Caused by 1/more micro-organisms

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2
Q

LO1: Microbiology of Acute Infectious Disease

A

1) Bacterial
- C.difficle, Vibrio cholera, E.coli, Shigella spp,
Salmonella typhi, Campylobacter jejuni

2) Protozoal
- Giardia intestinalis, Entamoeba histolytica, Cryptosporidium parvum

3) Viral (Most common)
- Noravirus, rotavirus, adenovirus

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3
Q

Methods to diagnose Acute Infectious Disease

A

1) Fecal occult blood - Non-specific, look for blood
in stools
2) Ova & parasite - By microscopy
3) Stool cultures - Takes few days, so not commonly done
4) PCR - More rapid, can look for multiple targets @ once
Quite ex

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4
Q

Who are diagnostic tests for Acute Infectious Diseases reserved for?

A
  • Severe illness
  • Persistent fever
  • Bloody stools
  • Immunosuppression
  • Unresponsive to treatment
  • Usually not indicated, most cases are self-limiting
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5
Q

How to prevent Acute Infectious Diseases?

A

1) Good hand & food hygiene practices
2) Vaccinations
- For travellers to endemic areas: Cholera, typhoid
- 6months-5y/o: Rotavirus

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6
Q

Treatment of Acute Infectious Diseases

A

Non-pharmacological:

  • Early re-feeding as tolerated
  • Easily digestible food (eg. cereal, bananas)

Pharmacologic

  • Self-care: Oral rehydration therapy, anti-peristaltics, adsorbents, probiotics
  • Antibiotics (for PR3124) [MOST cases self-limiting]
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7
Q

Indications for antibiotics for Acute Infectious Diseases

A

1) Severe disease
- Fever with bloody diarrhoea/ mucoid stools/ severe abdominal pain

2) Sepsis
3) Immunocompromised

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8
Q

Clinical benefits of antibiotics for Acute Infectious Diseases

A

1) Decrease duration of symptoms (1-2 days)

2) Decrease morbidity & mortality

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9
Q

Antibiotic regimen for Acute Infectious Diseases

A

1) IV Ceftriaxone 2g Q24h
2) PO Ciprofloxacin 500mg BD (if can’t tolerate B-lactam)

Duration of therapy: 3-5 days

  • May be extended in bacteremia/ extra intestinal infections/ immunocompromised
  • Rarely need to think about stepping down to PO
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10
Q

What is Clostridioides difficile?

A
  • Gram (+), spore-forming anaerobic bacillus
  • -> Produces toxins A & B
  • Most common cause of nosocomial diarrhoea
  • Increases duration of hospitalization & healthcare cost
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11
Q

How is Clostridioides difficile transmitted?

A
  • Fecal-oral route
  • Contaminated environmental surfaces
  • Hand carriage by healthcare workers

(Often within hospital envt, C.diff form spores hence infected persons can be asymptomatic)

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12
Q

Pathogenesis of Clostridioides difficile

A
  • Normal gut flora is altered by broad-spectrum antibiotics
  • C. difficile contains endospores that can survive acidity of stomach & reach the large intestine
  • C. difficile flourishes in colon, produces toxins A & B that cause mucosal damage
  • -> Bleeding, symptoms of C. difficile like fever, crampy abdominal pain, diarrhoea
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13
Q

Risk factors for C. difficle

A

1) Healthcare exposure
- Prior hospitalisation
- Duration of hospitalisation
- Long-term care facilities/ nursing homes

2) Pharmacotherapy
- Systemic antibiotics (no. of agents, duration)
- High risk Abx: Clindamycin, fluoroquinolones
2nd gen Cephalosporins
- Use of gastric acid suppressive therapy
(Easier for spores to get into colon)

3) Patient-related factors
- Multiple/severe comorbidities
- Immunosupression
- Advanced age > 65yo
- History of CDI (May have recurrence)

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14
Q

Clinical presentations of C. difficile

A

1) Mild
- Loose stools, abdominal cramps

2) Moderate
- Fever, nausea, malaise
- Ab cramps & distension
- Leukocytosis
- Hypovolemia

3) Severe/fulminant (rare but serious)
- Eg. ileus, toxic megacolon, pseudomembrance colitis, perforation, death

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15
Q

Process of diagnosis for C. difficle

A

1) Clinical suspicion (Don’t have to be hospitalised/ on antibiotics)
- Unexplained + new onset of diarrhoea (ie. >= 3 unformed stools in 24hrs) OR
- Radiologic evidence of ileus/ toxic megacolon

2) Confirmatory test/ finding
- (+) stool test result for C.difficle/ its toxins OR
- Histopathologic findings of pseudomembranous colitis

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16
Q

Diagnostic tests for C. difficile

A

1) Nucleic acid amplification test (NAAT)
- i) Toxin enzyme immunoassay (EIA): Looks for toxin A/B
- ii) Glutamate dehydrogenase (GDH) EIA:
Looks for enzyme

2) PCR

(Both have fast turnaround)

  • Cultures not routinely performed due to long turnaround time
  • Do not test asymptomatic patients
    (Based on clinical suspicion)
  • Do not repeat testing in < 7 days (waste time & money)
  • Do not perform test of cure
    –> Only monitor resolution of symptoms, don’t need to ensure clear of C. diff
17
Q

Infection control of C. difficile

A

Healthcare setting:

  • Practice hand hygiene
  • Contact precautions recommended for 48hrs after diarrhoea resolves (gloves, gown, wash hands with soap & water)

At home:

  • Wash hands with water & soap after bathroom
  • Use separate bathroom if possible
  • Clean toilets, linens, towels, clothing with bleach
18
Q

When to recommend empiric CDI treatment?

A

1) Fulminant CDI

2) Substantial delay (>48h) in diagnostics

19
Q

Antibiotic regimen for C. difficile (1st episode)

A

Non-Severe (WBC < 15, SCr < 133):
i) PO Vancomycin 125mg QDS or
ii) PO Fidaxomicin 200mg BD
(Alternative) PO Metronidazole 400mg TDS

Severe (WBC >= 15, SCr >= 133):

i) PO Vancomycin 125mg QDS or
ii) PO Fidaxomicin 200mg BD

Fulminant (Hypotension/ Ileus/ Megacolon):
i) IV Metronidazole 500mg Q8h +
PO Vancomycin 500mg QDS
(+/-) PR Vancomycin 500mg QDS

Duration: 10 days (May extend to 14 if symptoms not completely resolved)

20
Q

Why is Metronidazole still used locally?

A
  • Cost & logistic consideration
    (PO Vanco is prepared by compounded IV form to oral syringes)
  • Avoid repeated/prolonged courses
21
Q

Benefits & Drawbacks of Fidaxomicin

A
  • Narrow spectrum
  • Lower MIC vs Metronidazole/Vancomycin
  • Significant PAE
  • Less alteration of normal gut flora
  • May improve cure in immunocompromised patients

HOWEVER…

  • $$$
  • Hence, limited to severe &/or recurrent cases non-responsive to max standard therapy
22
Q

Antibiotic regimen for C. difficile (Recurrence)

A

1st recurrence:
[Metronidazole initially]: PO Vanco 125mg QDS x 10days
[1st line initially]: PO Vanco taper/
PO Fidaxomicin 200mg BD x 10days

2nd/subsequent recurrence:
i) PO Fidaxomicin 200mg BD x 10days
ii) PO Vancomycin taper
iii) PO Vancomycin 125mg QDS x 10days, 
    followed by Rifaximin 300mg TDS x 20days
iv) Fecal microbiota transplant
23
Q

Monitoring of C. difficile therapy

A
  • Clinical improvement: ~ 5-7days

Do not continue C. difficle for concurrent antibiotics:

  • -> Assess for indication to continue systemic
  • Stop systemic –> C. diff Abx –> Continue systemic
  • SERIOUS (eg. DFI): No choice, use concurrently
24
Q

Probiotics (Role, guidelines)

A

Contain: Saccharomyces boulardii/ Lactobacillus spp

Proposed mechanism: Maintain/restore healthy gut flora

Guideline recommendations:

  • Not recc for routine use to prevent/treat CDI
  • No harm to try unless immunocompromised
25
Q

Role of Anti-mobility agents?

Eg. loperamide, atropine, diphenoxylate

A

To provide symptomatic relief for diarrhoea by inhibiting contraction of intestinal smooth muscle

  • Limited role in infectious diarrhoea

PR3124 (16 decks)

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